Light emitting diode waveguide assemblies for illuminating refrigerated areas

ABSTRACT

An LED assembly for illuminating a refrigerated area includes a conductive base, a plurality of LED modules coupled to the conductive base, and a waveguide configured to direct light generated by the plurality of LED modules into the refrigerated area by reflecting and refracting light generated by the plurality of LED modules. The waveguide is located substantially within the refrigerated area. The LED assembly also includes an external heat sink coupled to the reflector base, and configured to conduct heat away from the conductive base. The external heat sink is mounted substantially outside the refrigerated area. The external heat sink can include an integral cooling channel. The LED assembly can also include an external cooling doom configured to provide cooling for the external heat sink.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part application of U.S. application Ser. No.11/670,981, filed on Feb. 3, 2007, pending, and entitled “Light EmittingDiode Modules for Illuminated Panels”, incorporated by reference in itsentirety; and co-pending and concurrently filed application Ser. No.______, (Attorney Docket No. IM 0701) filed Mar. 29, 2007, entitled“Light Emitting Diode Assemblies for Illuminating Refrigerated Areas”,by George K. Awai, Michael D. Ernst and Alain S. Corcos, which isincorporated by reference herein for all purposes.

BACKGROUND OF THE INVENTION

This invention relates generally to illuminating panels. Moreparticularly, this invention relates to light emitting diode (LED)modules for illuminating refrigerated areas.

Refrigerated display areas, such as supermarket freezers, make use ofinterior case lighting to illuminate products and to attract shoppers.In addition, the lighting should generate minimal heat so as to reducecooling requirements and avoid spoilage of the displayed food.

Fluorescent lighting are commonly used and are mounted vertically alongthe inside edge of the glass display doors of refrigerated areas.Although fluorescent lighting generate less heat and are more efficientthan incandescent lighting, fluorescent lighting suffer from decreasedlight output and reduced lamp life when operated in cold temperatureenvironments. Florescent lighting also produces diffused light patternsand hence do not illuminate the food products efficiently.

Recent attempts at replacing florescent lighting with LEDs resulted invery limited success for several reasons. While the compact size anddurability of LEDs makes them suitable for compact edge lighting forilluminated display doors, LEDs, especially high-powered LEDs, generatea substantial amount of heat which substantially increase cooling loadof the refrigerated areas.

It is therefore apparent that an urgent need exists for LEDassembly/structures that are suitable for evenly and efficientlyilluminating refrigerated displays, and is easy to manufacturer, easy tomaintain, shock resistant, impact resistant, portable, cost effective,and have long lamp-life.

SUMMARY OF THE INVENTION

To achieve the foregoing and in accordance with the present invention,light emitting diode (LED) assemblies for illuminating refrigerateddisplay areas are provided. Such LED assemblies can be operated veryefficiently, cost-effectively and with minimal maintenance onceinstalled in the field.

In accordance with one embodiment of the invention, an LED assemblyprovides illumination for a refrigerated area, the LED assemblyincluding a conductive base, a plurality of LED modules coupled to theconductive base, and a waveguide configured to direct light generated bythe plurality of LED modules into the refrigerated area by reflectingand refracting light generated by the plurality of LED modules. Thewaveguide is located substantially within the refrigerated area.

The LED assembly also includes an external heat sink coupled to thereflector base, and configured to conduct heat away from the conductivebase. The external heat sink is mounted substantially outside therefrigerated area. The external heat sink can include an integralcooling channel. The LED assembly can also include an external coolingdoom configured to provide cooling for the external heat sink.

In some embodiments, at least one of the plurality of LED modulesincludes an LED base, an LED located substantially within the LED baseand configured to generate a light beam, an inner beam director, and anouter beam director. The interface between the inner beam director andthe outer beam director is shaped to refract and/or reflect the lightbeam along the interface, thereby narrowing a substantial portion of thelight beam into the refrigerated area.

These and other features of the present invention will be described inmore detail below in the detailed description of the invention and inconjunction with the following figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present invention may be more clearly ascertained, oneembodiment will now be described, by way of example, with reference tothe accompanying drawings, in which:

FIG. 1 is a front view showing three illuminated doors for arefrigerated space in accordance with the invention;

FIGS. 2A, 2B are a cross-sectional side view of one of the illuminatedwall pillars for the refrigerated area of FIG. 1 and also shows displayshelves;

FIGS. 3A-3D are cross-sectional views of several embodiments of LEDassemblies for the illuminated pillar of FIG. 2A;

FIG. 4 illustrates a variant of the embodiment shown in FIG. 3B;

FIGS. 5A-5C are cross-sectional views of additional embodiments of LEDassemblies for the illuminated pillar of FIG. 2A;

FIG. 6 illustrates a variant of the embodiment shown in FIG. 5B;

FIGS. 7A, 7B and 7C are an isometric view, a cut-away view and across-sectional view, respectively, of an LED module 700 in accordancewith an aspect of the present invention;

FIGS. 7D, 7E are cross-sectional views of a substantially reflectivemodule and a refractive/reflective module in accordance with the presentinvention;

FIGS. 8A-10E are cross-sectional views of additional embodiments of theLED modules of the present invention; and

FIG. 11 is a cross-sectional view of another embodiment of LED assemblyfor the illuminated pillar of FIG. 2A.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in detail with reference toseveral embodiments thereof as illustrated in the accompanying drawings.In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one skilled in the art, that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process steps and/or structureshave not been described in detail in order to not unnecessarily obscurethe present invention. The features and advantages of the presentinvention may be better understood with reference to the drawings anddiscussions that follow.

In accordance with the present invention, FIG. 1 is a front view showingan illuminated refrigerated display area 100 with a plurality of doorsincluding doors 110, 120, 130. Door 110 includes a transparent panel112, a frame 114 and a door handle 116. For clarity, doors 120, 130 areshown partially cut-away to expose a support pillar 105 and a horizontalspan 108.

FIG. 2A is a cross sectional side view showing pillar 105 of FIG. 1 andalso shows display shelves 210 a, 210 b . . . 210 k supported bycorresponding brackets 215 a, 215 b . . . 215 k. An LED assembly 240(described in greater detail below) is attached to the refrigerated sideof vertical pillar 105. LED assembly 240 can also be coupled to anexternal heat sink 245 via heat pipes 248 a, 248 b, 248 c, 248 d . . .and 248 m, thereby enabling LED assembly 240 to dissipate heat outsidethe refrigerated area.

FIGS. 3A-3D are cross sectional views of exemplary embodiments 300A,300B, 300C, 300D for the LED assembly 240 of the present invention, andcorrespond to cross section line 1A-1A of FIG. 1. Referring first toFIG. 3A, LED assembly 300A includes doom lens 310, reflector base 320 a,LED boards 362, 364, internal heat sink 350 a, conductors 342, 344, 346and external heat sink 340 a.

Doom lens 310 is located substantially within the refrigerated side ofwall 330, while external heat sink 340 a is located on the ambient sideof wall 330. Lens 310 can be made from a suitable transparent ortranslucent material such as glass or a suitable polymer, e.g., acrylicor polycarbonate. Depending on the specific implementation, lens 310 canbe clear or frosty. In addition, lens 310 can have opticalcharacteristics such as that of a Fresnel lens which can be incorporatedonto the protected inner surface of lens 310.

Each LED boards 362, 364 includes a row of LED modules and the circuitryfor coupling the LED modules to a suitable power source (not shown).Suitable LED modules are commercially available from OSRAM OptoSemiconductors Inc. of Santa Clara, Calif., Nichia Corporation ofDetroit, Mich., Cree Inc. of Durham, N.C., or Philips Lumileds LightingCompany of San Jose, Calif. LED boards 362, 364 may also include some ofthe power circuitry components such as resistors and may also includesensors such as temperature sensors and/or illumination level sensors.

LED boards 362, 364 are mounted on reflector base 320 a which focuseslight rays 371 a, 372 a and rays 381 a, 382 a into rays 371 b, 372 b andrays 381 b, 382 b, respectively, onto the display area located in therefrigerated side of wall 330.

Reflector base 320 a which is coupled to internal heat sink 350 a.Conductors 342, 344, 346 couple internal heat sink 350 a to externalheat sink 340 a through wall 330. As a result, the heat generated by LEDboards 362, 364 can be conducted from reflector base 320 a to internalheat sink 350 a, and in turn to external heat sink 340 a via conductors342, 344, 346.

In accordance with the present invention, the heat dissipationcapability of reflector base 320 a and heat sinks 350 a, 340 a isfurther enhanced by lens cooling channel 315, base cooling channel 325 aand heat sink cooling channel 355 a. As illustrated by both FIGS. 1 and2A, in this embodiment cooling channels 315, 325 a, 355 a are orientedvertically and hence are capable of efficiently dissipating heat via airconvection from ambient air drawn from outside the refrigerated space,thereby substantially reducing the amount of heat dissipated into therefrigerated space. Circulation of cooling air can also be from forcedair cooling. It is also possible to divert some of the chilled air fromthe refrigerated space into one or more of cooling channels 315, 325 a,355 a. While air is used as the exemplary cooling medium in thisembodiment, it is also possible to use other suitable fluids and gasesknown to one skilled in the refrigeration arts such as Freon, R12 andR134a.

FIG. 3B shows a variant 300B of the LED assembly 240, in which thecooling surface area of heat sink cooling channel 355 b is substantiallyincreased by introducing ribs or groves into the internal surface ofchannel 355 b thereby enhancing the heat dissipating capability of LEDassembly 300B and substantially reducing the heat dissipated into therefrigerated space. In this embodiment, ribs or groves can also beincorporated onto the surface of external heat sink 340 b to furtherincrease the heat dissipation capability of external heat sink 340 binto the ambient air.

Other modifications are also possible. For example, as shown in FIG. 3C,light rays 371 a, 372 a, 381 a, 382 a produced by yet another embodiment300C of LED assembly 240 are focused into rays 371 b, 372 b, 381 b, 382b, respectively, by a pair of curved reflectors located on reflectorbase 320 c. The shape and orientation of these reflectors of base 320 ccan vary in accordance to the width and depth of display shelves 210 a,210 b . . . 210 k. As shown in FIG. 3D, in some implementations, LEDassembly 300D can have three LED boards 362, 364, 368.

Referring again to FIG. 1, it is also possible to mount any one of LEDassemblies 300A, 300B, 300C and 300D vertically along the refrigeratedside of door frame 114 and corresponding to cross section line 1B-1B.

FIG. 4 is a cross sectional view of yet another embodiment 400 for theLED assembly 240 of the present invention, and corresponds to sectionline 1C-1C of door frame 114. External heat sink 440 is coupled tointernal heat sink 350 b via heat conducting connectors 442, 444. Inthis embodiment, external heat sink 440 also includes a ribbed coolingchannel 448. As a result, external heat sink 440 is shaped to alsofunction as a door handle which is now warmer and more comfortable for acustomer to use because external heat sink 440 is now dissipating heatgenerated by LED assembly 400.

Referring back to FIG. 1, instead of vertical mounting, LED assemblies300A, 300B and 300C can also be modified to operate in a horizontalorientation along a top front span 108 of refrigerated area 100corresponding to section line 1E-1E, by for example eliminating one ofthe LED board and also using forced air cooling. This horizontal variantof LED assemblies 300A, 300B and 300C can also be mounted along the topof door frame 114 corresponding to section line 1D-1D.

Alternatively, as shown in FIG. 2B, it is also possible to horizontallymount LED assemblies 242 a, 242 b . . . 242 k, with each LED assemblyspanning vertical pillars, e.g., spanning pillar 105 and the adjacentpillar located between doors 110, 120, of refrigerated area 100.

FIGS. 5A, 5B, 5C are additional cross sectional views of additionalvariants 500A, 500B, 500C for exemplary vertical LED assembly 240 andhorizontal LED assemblies 242 a, 242 b . . . 242 k in accordance withthe present invention.

Referring first to FIG. 5A, LED assembly 500A includes an opticalwaveguide 510 a, LED board 560, conductive base 545, thermal barrier535, external heat sink 540 a and external cooling doom 520. Waveguide510 a is located substantially within the refrigerated side of wall 530,while the rest of assembly 500A, including cooling doom 520, is locatedsubstantially on the ambient air side of wall 530.

LED board 560 includes a row of LED modules and the circuitry forcoupling the LED modules to a suitable power source (not shown).Suitable LED modules are commercially available from OSRAM OptoSemiconductors Inc. of Santa Clara, Calif., Nichia Corporation ofDetroit, Mich., Cree Inc. of Durham, N.C., or Philips Lumileds LightingCompany of San Jose, Calif. LED board 560 may also include some of thepower circuitry components such as resistors and may also includesensors such as temperature sensors and/or illumination level sensors.

By repeatedly reflecting and refracting light rays generated by LEDboard 560, waveguide 510 a provides a pair of evenly-illuminated andfocused light beams into the refrigerated area. For example, light ray571 a is internally reflected as light ray 571 b, which is refractedoutside waveguide as light ray 571 c and also internally reflected aslight ray 571 d, and further refracted and reflected into light rays 571e, 571 f, respectively. Light ray 571 f is then refracted as light ray571 g and reflected as light ray 571 h, which in turn is refracted andreflected into light rays 571 k, 571 m, respectively.

Similarly, light ray 572 a is internally reflected as light ray 572 b,which is refracted outside waveguide as light ray 572 c and alsointernally reflected as light ray 572 d, and further refracted andreflected into light rays 572 e, 572 f, respectively. Light ray 572 f isthen refracted as light ray 572 g and reflected as light ray 572 h,which in turn is refracted and reflected into light rays 572 k, 572 m,respectively.

LED board 560 is mounted on conductive base 545 which in turn is coupledto external heat sink 540 a. As a result, the heat generated by LEDboard 560 can be conducted by base 545 to external heat sink 540 a, andthen dissipated outside the refrigerated area.

In accordance with the present invention, the heat dissipationcapability of heat sink 540 a is further enhanced by cooling channel 525formed by external cooling doom 520. As illustrated by both FIGS. 1 and2, in this embodiment cooling channel 525 is oriented vertically andhence is capable of efficiently dissipating heat via air convection fromambient air drawn from outside the refrigerated space, therebysubstantially reducing the amount of heat dissipated into therefrigerated space. Circulation of cooling air can also be from forcedair cooling. It is also possible to divert some of the chilled air fromthe refrigerated space into cooling channel 525.

FIG. 5B shows a variant 500B of the LED assembly 240, in which thecooling surface area of heat sink 540 b is substantially increased byincorporating ribs or groves onto the surface of external heat sink 540b thereby enhancing the heat dissipating capability of LED assembly 300Band further reducing the heat dissipated into the refrigerated space byLED board 530 and waveguide 510 a.

Other waveguide profiles are also possible and include straight,tapered, and curved shapes and combinations thereof. For example, asshown in FIG. 5C, waveguide 510 c has a straight body and a curved tip.

FIG. 6 is a cross sectional view of yet another embodiment 600 for theLED assembly 240 of the present invention, and corresponds to crosssection line 1C-1C of door frame 114. In this embodiment, external heatsink 640 also includes a cooling channel 648 and is shaped as a doorhandle which is now warmer and more comfortable for the customer's usebecause external heat sink 640 is now dissipating heat from LED board560 via base 645.

In some embodiments, since white LEDs are not the most efficient emitterof light, it is also possible for LED board 560 to transmit light in thesubstantially blue-to-ultraviolet range into optical waveguides 510 a,510 c that have been impregnated with phosphors, enabling waveguides 510a, 510 c to convert the blue-to-ultraviolet light into white light orany colored light within the visible spectrum.

FIGS. 7A, 7B and 7C are an isometric view, a cut-away view and across-sectional view, respectively, of a highly efficient LED module 700in accordance with another aspect of the present invention. LED module700 includes a base 710, an outer beam director 720, an inner beamdirector 730, and an LED 790.

Suitable materials for base 710 include high temperature acrylicco-polymer and for beam directors 720, 730 include acrylic and opticalgrade silicone. Depending on the application, beam directors 720, 730can be an optically clear material or slightly diffusive. LEDs suitedfor LED 790 include commercially available LEDs from OSRAM OptoSemiconductors Inc. of Santa Clara, Calif. such as model numbersLW-E6SG, LW-G6SP and LW-541C.

Since most efficient LEDs typically generate substantially more blue andultraviolet light, LED 790 can be geometrically coated with a suitablephosphor layer, also known as conformal phosphor coating (not shown),known to one skilled in the art so as to produce a compact LED capableof generating a whiter light beam whose spectrum is better suited forilluminating display panels. This is possible because an even phosphorcoating minimizes chromatic separation of the white light generated byLED 790. It is also possible to use LEDs that generate a whiter lightspectrum without an additional phosphor layer.

While LEDs have been used for illumination applications, mostcommercially available LED packages are designed to generate a fairlywide-angled and evenly-spread beam of light for applications such asarea lighting. Hence, these off the shelf LED packages are not suitablefor edge illumination of display panels because a wide-angled beam willgenerate a substantially higher level of illumination closer to the edgeof the display panels resulting in uneven illumination.

In contrast, light sources for edge illumination of the display panelsshould be capable of generating a substantially narrow beam ofpenetrating light so as to evenly illuminate the central portions of thedisplay panels which can have a large display surface area.

In accordance with one aspect of the present invention as illustrated byFIG. 7C, the deep penetration needs are accomplished primarily byreliance on the refractive and/or reflective properties of the interfacebetween outer beam director 720 and inner beam director 730. Therefractive and/or reflective properties can be controlled by selectingsuitable interface profiles and N index values. Suitable profiles forbeam director interfaces include parabolic and elliptical curved shapes.Suitable N values include for example, N1 being approximately 1.33 to1.41 and N2 being approximately 1.49 to 1.6 for beam directors 720 and730, respectively. In some embodiments, most of the light produced byLED module 700 is substantially concentrated within an approximately 40degree beam angle.

Accordingly, exemplary light rays 760 a, 770 a produced by LED 790 arerefracted by beam directors 720, 730 into rays 760 b, 770 b,respectively. Light rays 760 b, 770 b are further refracted by theexternal surface of outer beam director 720 into rays 760 c, 770 c, andthereby enabling LED module 700 to generate a substantially narrowerbeam of light than that initially produced by LED 790.

FIG. 7D shows a modified LED module 700D in which a reflective layer 740is added between outer beam director 720 and inner beam director 730thereby enhancing the reflective properties of the interface betweenbeam directors 720, 730. Reflective layer 740 can be formed bytechniques well known in the art including vapor and electrostaticdeposition. Light rays 760 a, 770 a produced by LED 790 are reflected bylayer 740 into rays 760 b, 770 b, respectively, enabling LED module 700Dto produce a substantially narrow and penetrating beam of lightincluding rays 760 c, 770 c.

As discussed above, a substantially wide-angled beam will betterilluminate the surface of display panels closest to the light source,while a substantially narrow light beam is especially beneficial fordeeper penetration of relatively large display panels. At first blush,the shallow penetration and deep penetration needs appear to becompeting requirements.

In accordance with another aspect of the present invention asillustrated by the cross-sectional view of FIG. 7E, both shallow anddeep penetration needs can be accomplished by reliance on a suitablebalance between the reflective and/or refractive properties of theinterface between outer beam director 720 and inner beam director 730.This delicate refractive/reflective balance can be controlled byselecting suitable materials with suitable relative N values fordirectors 720, 730, e.g. N1 being approximately 1.33 to 1.41 and N2being approximately 1.49 to 1.6, respectively.

For example, light ray 760 is refracted into ray 764 b and alsoreflected as ray 762 b, while light ray 770 is reflected into ray 774 band also reflected as ray 772 b. Hence, LED module 700 is now capable ofproducing a substantially narrow beam of light, e.g., rays 762 c, 772 c,for penetrating the display panel while still able to produce enoughshorter range light rays, e.g., rays 764 c, 774 c to illuminate thecloser surface of the display panel. As a result, LED module 700 iscapable of generating variable intensity ranges at various beam angles,e.g., 80% intensity at between 0 and 40 degrees, and 20% intensitybetween 40 to 80 degrees.

Several additions and modifications to LED module 700 are also possibleas shown in the exemplary cross-sectional views of FIGS. 8A through 10E.Many other additions and modifications are also possible within thescope of the present invention.

FIGS. 8A and 8B show embodiments 800A, 800B with substantially straightinterface profiles between outer beam directors 820 a, 820 b and innerbeam directors 830 a, 830 b, respectively. Note the cone-shaped innerbeam director 830 a and cylindrical-shaped inner beam director 830 b.

FIGS. 9A-9C illustrate additional embodiments with multiple refractiveand/or reflective interfaces introduced by adding intermediate beamdirectors, i.e., directors 932 of module 900A, directors 934, 938 ofmodule 900B, and director 932 of module 900C. As discussed above, themultiple interfaces can have refractive and/or reflective propertiesdefined by suitable interface profiles and N values.

For example, light rays 960 a, 970 a produced by LED 790 are refractedby the interface between beam directors 930, 932 into rays 960 b, 970 b,respectively. Light rays 960 b, 970 b are further refracted by theexternal surface of intermediate beam director 932 into rays 960 c, 970c.

Similarly, light rays 965 a, 975 a produced by LED 790 are refracted bythe interface between beam directors 932, 930 into rays 965 b, 975 b,respectively, which are in turn further refracted by the interfacebetween beam directors 920, 932 into rays 965 c, 975 c. Light rays 965c, 975 c are then refracted by the external surface of outer beamdirector 920 into rays 765 d, 775 d.

As a result, a focused beam of light including exemplary light rays 965d, 960 c, 970 c, 975 d is formed, enabling LED module 900A to generate asubstantially narrower and penetrating beam of light than that initiallyproduced by LED 790. As discussed above, the balance between therefractive and/or reflective properties of beam directors 920, 932, 930can be controlled by selecting suitable materials with suitable relativeN values for directors 920, 932, 930. In addition, beam directors 920,932, 930 can be optically clear or slightly diffusive.

The cross-sectional views of FIGS. 10A-10E show additional possible LEDmodule embodiments, e.g., module 1000A without an inner beam director;module 1000B with a concave-topped inner beam director 1032; module1000C with a convex-topped inner beam director 1034; module 1000D has anexposed LED 790 and a substantially reflective layer 1042 with a curvedprofile; and module 1000E has an exposed LED 790 and a substantiallyreflective layer 1044 with a cone-shaped profile.

FIG. 11 shows how the focused-beam LED modules described above, e.g.,LED modules 700, 800A, 800B . . . 1000E can be incorporated into the LEDassemblies 240 and 242 a of the present invention. In this example, LEDboards 1162, 1164 each include at least one focused-beam LED module, andhence LED boards 1162, 1164 can be mounted onto base 1120 of LEDassembly 1100 without the need for external reflectors. Depending on theapplication, it may also be possible to combine focused-beam LED moduleshaving different beam angles onto LED boards 1162, 1164.

Many modifications and variations are possible. For example, LEDassemblies 300A, 300B, 300C, 400, 500A, 500B, 600, 1100 can be dimmableby adding a variable current control circuitry. An infrared red sensorcan also be added to the control circuitry of assemblies 300A, 300B,300C, 400, 500A, 500B, 600, 1100 so that the refrigerated area isilluminated when a potential customer enters the detection field therebydimming or turning on and off in an appropriate manner.

Other modifications and variations are also possible. For example, it isalso possible to sense the ambient light level of the surrounding andadjust the light output of the panels accordingly, thereby conservingpower. The present invention can also improve the quality and quantityof light transmitted by other non-point light sources such as neon andfluorescent light sources.

In the above described embodiments, frame members of doors 110, 120 andthe heat conducting components of LED assemblies 300A, 300B, 300C, 400,500A, 500B, 600 can be manufactured from aluminum extrusions. The use ofany other suitable rigid and heat-conducting framing materials includingother metals, alloys, plastics and composites such as steel, bronze,wood, polycarbonate, carbon-fiber, and fiberglass is also possible.

In sum, the present invention provides improved LED assemblies forevenly illuminating refrigerated areas that is easy to manufacturer,easy to maintain, shock resistant, impact resistant, cost effective, andhave long lamp-life.

While the present invention has been described with reference toparticular embodiments, it will be understood that the embodiments areillustrative and that the inventive scope is not so limited. Inaddition, the various features of the present invention can be practicedalone or in combination. Alternative embodiments of the presentinvention will also become apparent to those having ordinary skill inthe art to which the present invention pertains. Such alternateembodiments are considered to be encompassed within the spirit and scopeof the present invention. Accordingly, the scope of the presentinvention is described by the appended claims and is supported by theforegoing description.

1. A light emitting diode (LED) assembly useful for illuminating arefrigerated area, the LED assembly comprising: a conductive base; aplurality of LED modules coupled to the conductive base; a waveguideconfigured to direct light generated by the plurality of LED modulesinto the refrigerated area by reflecting and refracting light generatedby the plurality of LED modules, and wherein the waveguide is furtherconfigured to operate substantially within the refrigerated area; and anexternal heat sink coupled to the reflector base, and configured toconduct heat away from the conductive base, wherein the external heatsink is further configured to be mounted substantially outside therefrigerated area.
 2. The LED assembly of claim 1 further comprising anexternal cooling doom configured to provide cooling for the externalheat sink.
 3. The LED assembly of claim 1 wherein the external heat sinkincludes an external sink cooling channel.
 4. The LED assembly of claim1 wherein the waveguide is impregnated with a phosphor.
 5. A lightemitting diode (LED) assembly useful for illuminating a refrigeratedarea, the LED assembly comprising: a conductive base; a plurality of LEDmodules coupled to the conductive base; a waveguide configured to directlight generated by the plurality of LED modules into the refrigeratedarea by reflecting and refracting light generated by the plurality ofLED modules, and wherein the waveguide is further configured to operatesubstantially within the refrigerated area; an external heat sinkcoupled to the reflector base, and configured to conduct heat away fromthe conductive base, wherein the external heat sink is furtherconfigured to be mounted substantially outside the refrigerated area;and wherein at least one of the plurality of LED modules includes: anLED base; an LED located substantially within the LED base andconfigured to generate a light beam; an inner beam director; and anouter beam director, wherein an interface between the inner beamdirector and the outer beam director is shaped to refract and reflectthe light beam along the interface, thereby narrowing a substantialportion of the light beam.
 6. The LED assembly of claim 5 wherein theLED has a geometrically coated phosphor layer.
 7. The LED assembly ofclaim 5 wherein the interface between the inner beam director and theouter beam director includes an intermediate beam director configured tofurther refract and reflect the light beam generated by the LED.
 8. TheLED assembly of claim 5 wherein the shaped interface is curved.
 9. TheLED assembly of claim 7 wherein the shaped interface is highlyreflective.
 10. The LED assembly of claim 5 wherein the intermediatebeam director is highly reflective.
 11. The LED assembly of claim 5wherein the inner beam director has a first N value and the outer beamdirector has a second N value, and wherein the first N value issubstantially lower than the second N value.
 12. The LED assembly ofclaim 5 further comprising an external cooling doom configured toprovide cooling for the external heat sink.
 13. The LED assembly ofclaim 5 wherein the external heat sink includes an external sink coolingchannel.
 14. The LED assembly of claim 5 wherein the waveguide isimpregnated with a phosphor.